The present invention relates to an optical waveguide module-mounted device which comprises a case and an optical waveguide module mounted in the case, the module being comprised of an optical waveguide chip and optical fibers connected to the chip. More particularly, the present invention relates to an optical waveguide module-mounted device used in the field of optical communication.
The recent development of optical communication technology has demanded optical waveguide module-mounted devices, such as optical branching elements and optical multiplexers, with higher cost performance and higher reliability. In general, the conventional optical waveguide module-mounted device is composed of an optical waveguide chip and optical fibers for optical input/output, connected to the terminal end surfaces of the optical waveguide chip.
When the optical waveguide module is put in use in communication system, it is generally necessary to protect the module by a package to enhance the reliability. The package provides resistance to external mechanical impact, thereby improving long-term reliability. When an optical waveguide is connected to optical fibers, a UV-setting resin is generally used as an adhesive for connection. It is known that the long-term adhesive property of the UV-setting resin is deteriorated due to intrusion of moisture. Therefore, it is of importance that the connecting portion of the optical waveguide module is protected by a case or similar means so that the connecting portion is not exposed to moisture (see Japanese Patent No. 3,070,028).
FIG. 1 shows a longitudinal cross section of a conventional optical waveguide module-mounted device, which comprises an optical waveguide module composed of optical fibers 1 and an optical waveguide chip 2, connected in such manner that their axes are aligned with each other, and a cylindrical case 4 in which the module is fixed via element-fixing members 3. The optical fibers 1 are fixed in position with optical-fiber lead-in members 5. The optical fibers 1 and the optical waveguide chip 2 are enclosed by the cylindrical case 4 and the optical-fiber lead-in members 5.
FIG. 2 shows a cross section of another conventional optical waveguide module-mounted device. An optical waveguide module comprising optical fibers 1 and an optical waveguide chip 2, connected in such manner that their axes are aligned with each other, is fixed to a lower half case 6 (the case is formed of an upper half case and a lower half case) by resin 7. The optical fibers 1 are fixed in position with optical-fiber lead-in members 5, and the optical waveguide module-mounted device is sealed with the upper half case 8 of the upper-lower separation type case. The optical fiber 1 and the optical waveguide chip 2 are enclosed by the lower half case 6 and the upper half case 8 of the upper-lower separation type case and the optical-fiber lead-in members 5.
The optical-fiber lead-in member 5, used in conventional optical waveguide module-mounted devices as shown in FIGS. 1 and 2, is typically made of a flexible gummy resin, in order to enhance bending strength reliability of the optical fibers. FIG. 3 shows a condition of the conventional device, when the optical fiber is bent. As shown in FIG. 3, even when the bending direction of the optical fiber 1 is changed by external force, the lead-in member 5 is flexible enough to absorb the bend, thereby maintaining bending strength reliability of the optical fiber.
However, the structure of the conventional optical waveguide module-mounted device shown in FIG. 1 has problems in that, in order to fix the optical waveguide module comprised of the optical waveguide chip and the optical fibers connected to the chip to the inside of the cylindrical case, it is necessary to pass the optical waveguide module through the cylindrical case and the optical fibers through the optical-fiber lead-in members. In addition, for adhesion of the optical waveguide chip to the cylindrical-case via element-fixing members, special jigs are required due to the cylindrical shape. Further, the fixing portion cannot be visually checked from above the case and thus the workability becomes poor, resulting in additional working processes.
On the other hand, since the conventional optical waveguide module-mounted device shown in FIG. 2 is in the form of a box comprising an upper half and a lower half, as compared with the conventional case shown in FIG. 1, this shape allows visual checking of the portion of fixing the optical waveguide module to the case from above, and the workability is improved, leading to less working steps. However, more parts are necessary in this device, resulting in higher cost and more assembling steps, and the resultant device becomes costly.
In order to solve the above-mentioned problems, the present inventors proposed an optical waveguide module-mounted device formed of upper-lower separation type case member in co-pending U.S. patent application Ser. No. 10/104594, filed on Mar. 27, 2002 (based on Japanese Patent Application No. 2001-089644), assigned to the same assignee, which is incorporated herein by reference). Specifically, as shown in FIG. 4, an optical waveguide module comprising optical fibers 19 and an optical waveguide chip 18, connected in such manner that their axes are aligned with each other, is fixed to an optical waveguide-chip fixing groove of a lower half case 12 (the case is formed of an upper half case 11 and a lower half case 12) by resin (for fixing optical waveguide chip) 22. The optical fiber 19 is passed through an optical-fiber lead-in groove 13 and fixed in position by a sealant 21. At an internal position of the case, the optical fiber is further fixed to an optical-fiber fixing groove 14 by a resin (for fixing optical fiber) 20. The fixed fiber is sealed with the upper half case 11. The optical fibers 19 and the optical waveguide chip 18 are enclosed by the upper half case 11 and the lower half case 12.
Problems to be Solved by the Invention
In the case of the optical waveguide module-mounted device shown in FIG. 4, i.e. the device described in the prior application by the present inventors (U.S. patent application Ser. No. 10/104594), the case member is provided with the optical waveguide-chip fixing groove 17, the optical-fiber lead-in portions 13 and the optical-fiber fixing grooves 14, which is different feature from the conventional devices shown in FIGS. 1 and 2. With this multi-functional integrated upper-lower separation type case, the number of parts can be reduced and assemblage can be easily conducted. However, the multi-functional integrated upper-lower separation type case, used in the optical waveguide module-mounted device shown in FIG. 4, is generally made of a resin by injection molding or a metal by metal injection, from the viewpoint of lowering production cost. The resultant optical-fiber lead-in portion is rigid and hard. Therefore, the case has a problem in that, when the optical fibers are bent by external force at portions where the optical fibers are led out of the case, friction between the fiber and the case occurs, which may lower the quality of the optical fibers, resulting in low liability of the optical fibers.
In brief, the optical waveguide module-mounted device comprising the multi-functional integrated upper-lower separation type case shown in FIG. 4 has advantages of reducing the number of parts. In addition, since the case is comprised of open half cases, it is allowed to visually check the portions of fixing the optical waveguide module to the case from above and below, and thus the workability is improved, leading to less working steps. However, the case also has disadvantages in that, since the optical-fiber lead-in portions are made of a rigid resin or metal, bending strength reliability of the optical fibers is lowered when the optical fibers are abraded by the rigid case at the open potions.
One of features of the present invention is to provide a multi-functional integrated upper-lower separation type case, in which various functions (such as an optical-fiber lead-in portion) are integrated, wherein the optical-fiber lead-in portions are each comprised of an optical-fiber open groove and an optical-fiber lead-in groove, the optical-fiber open groove being more receded or deeper, as compared with the optical-fiber lead-in groove. With this structure, at a portion where the optical fiber is led out of the case, i.e. at open portion, the optical fiber and the multi-functional integrated upper-lower separation type case are not brought into contact to each other. As a result, an optical waveguide module-mounted device exhibiting excellent bending strength reliability of the optical fiber can be provided. In addition, the number of parts can be reduced, which attains easy assemblage.
More specifically stated, the present invention provides an optical waveguide module-mounted package containing an optical waveguide module in a separation type case, said module comprising an optical waveguide chip and a pair of optical fibers connected to said optical waveguide chip in the manner that the optical axes of said chip and said fibers are aligned with each other, wherein said separation type case has a pair of optical-fiber lead-in portions, each of said optical-fiber lead-in portion having an open groove at an open portion for leading said optical fiber into said separation type case, and an optical-fiber lead-in groove for positioning the optical fiber, which groove is connected to the inner end of the open groove, said open groove being deeper than said optical-fiber lead-in groove.
Preferably, the position of the open groove and that of the lead-in groove are defined so that the optical fiber is led into the open groove at or near the center of the open portion.
The separation type case preferably has an optical-fiber fixing groove which is connected to the inner end of the optical-fiber lead-in groove, and an optical waveguide-chip fixing groove for fixing the optical waveguide module, which groove is connected to the inner end of the optical-fiber fixing groove and is deeper than the optical-fiber fixing groove.
The separation type case is formed by combining two identical half cases, each half case being provided with a mating surface having one or more recess-protrusion pairs for fitting, said recess and said protrusion being fitted respectively over the protrusion and in the recess of the other half case.
The mating surfaces of the two half cases forming said separation type case are adhered to each other with a sealant, and preferably, the above-mentioned open groove is filled with a flexible sealant or resin.